Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
import queue

H,W=map(int,input().split())
c=["#"*(W+2)]+["#"+input()+"#" for _ in range(H)]+["#"*(W+2)]

ans=0
for i in range(H+2):
    for g in range(W+2):
        if c[i][g]==".":
            ans+=1

dist=[[-1]*(W+2) for _ in range(H+2)]
que=queue.Queue()
que.put((1,1))
dist[1][1]=0

while not que.empty():
    h,w=que.get()
    direction=[(0,-1),(0,1),(1,0),(-1,0)]
    for y,x in direction:
        if c[h+y][w+x]=="." and dist[h+y][w+x]==-1:
            que.put((h+y,w+x))
            dist[h+y][w+x]=dist[h][w]+1

if dist[H][W]==-1:
    print(-1)
else:
    print(ans-dist[H][W]-1)